Mass spectrometer

Abstract

A mass spectrometer is disclosed comprising an ion mobility spectrometer or separator and an ion guide arranged downstream of the ion mobility spectrometer or separator. A plurality of axial potential wells are created in the ion guide so that ions received from the ion mobility spectrometer or separator become confined in separate axial potential wells. The potential wells maintain the fidelity and/or composition of ions received from the ion mobility spectrometer or separator. The potential wells are translated along the length of the ion guide.

The invention claimed is: 
     
       1. A mass spectrometer comprising:
 an ion mobility separator; 
 an ion guide comprising a stack of electrodes arranged downstream of said ion mobility separator; 
 a voltage source for applying one or more voltages to the stack of electrodes for generating an axial potential; 
 an ion trap or a further ion guide upstream of said ion mobility separator; 
 a fragmentation or collision cell; and 
 a mass analyser disposed downstream of the ion guide. 
 
     
     
       2. A mass spectrometer as claimed in  claim 1 , wherein said mass analyser is selected from the group consisting of: (i) a quadrupole mass analyser; (ii) a 2D or linear quadrupole mass analyser; (iii) a Paul or 3D quadrupole mass analyser, (iv) a Penning trap mass analyser, (v) an ion trap mass analyser; (vi) a magnetic sector mass analyser; (vii) Ion Cyclotron Resonance (“ICR”) mass analyser (viii) a Fourier Transform Ion Cyclotron Resonance (“FTICR”) mass analyser, (ix) an electrostatic or orbitrap mass analyser; (x) a Fourier Transform electrostatic or Orbitrap mass analyser; (xi) a Fourier Transform mass analyser; (xii) a Time of Flight mass analyser; and (xiii) an orthogonal Time of Flight mass analyser. 
     
     
       3. A mass spectrometer as claimed in  claim 1 , further comprising a mass filter. 
     
     
       4. A mass spectrometer as claimed in  claim 3 , wherein said mass filter is arranged so that a mass filtering characteristic of said mass filter is progressively varied, increased or stepped. 
     
     
       5. A mass spectrometer as claimed in  claim 4 , wherein said mass filter is arranged so that ions having a first charge state are onwardly transmitted whereas ions having a second different charge state are substantially attenuated by said mass filter. 
     
     
       6. A mass spectrometer as claimed in  claim 3 , wherein said mass filter is operated as a high pass mass to charge ratio filter or a band pass mass to charge ratio filter. 
     
     
       7. A mass spectrometer as claimed in  claim 1 , wherein said ion guide comprises an ion funnel. 
     
     
       8. A mass spectrometer as claimed in  claim 1 , wherein said ion trap or further ion guide comprises an ion funnel. 
     
     
       9. A mass spectrometer as claimed in  claim 1 , wherein said ion mobility separator comprises a drift tube. 
     
     
       10. A mass spectrometer as claimed in  claim 1 , wherein said ion mobility separator has an axial length >300 mm. 
     
     
       11. A mass spectrometer comprising:
 an ion mobility separator; 
 an ion guide comprising an ion funnel arranged downstream of said ion mobility separator, said ion guide being arranged to receive ions from said ion mobility separator, and wherein said ion guide comprises a plurality of electrodes having apertures through which ions are transmitted in use, wherein at least some of said electrodes have apertures which become progressively smaller in size or in area; 
 AC or RF voltage means arranged and adapted to apply an AC or RF voltage to at least some of said plurality of electrodes of said ion guide in order to confine ions radially within said ion guide; and 
 a mass analyser disposed downstream of the ion guide. 
 
     
     
       12. A mass spectrometer as claimed in  claim 11 , further comprising an ion trap upstream of said ion mobility separator. 
     
     
       13. A mass spectrometer as claimed in  claim 11 , comprising a further ion guide upstream of said ion mobility separator. 
     
     
       14. A mass spectrometer as claimed in  claim 11 , further comprising a fragmentation or collision cell. 
     
     
       15. A mass spectrometer as claimed in  claim 11 , wherein said ion mobility separator comprises a drift tube having an axial length >300 mm. 
     
     
       16. A mass spectrometer comprising:
 an ion mobility separator comprising a drift tube having an axial length >300 mm; 
 an ion guide comprising an ion funnel arranged downstream of said ion mobility separator, said ion guide being arranged to receive ions from said ion mobility separator, and wherein said ion guide comprises a plurality of electrodes having apertures through which ions are transmitted in use, wherein at least some of said electrodes have apertures which become progressively smaller in size or in area; 
 AC or RF voltage means arranged and adapted to apply an AC or RF voltage to at least some of said plurality of electrodes of said ion guide in order to confine ions radially within said ion guide; 
 an ion trap or a further ion guide upstream of said ion mobility separator; 
 a fragmentation or collision cell; and 
 a mass analyser disposed downstream of the ion guide. 
 
     
     
       17. A mass spectrometer as claimed in  claim 16 , wherein said ion trap or further ion guide comprises an ion funnel. 
     
     
       18. A mass spectrometer as claimed in  claim 16 , wherein said mass analyser comprises a Time of Flight mass analyser or an orthogonal Time of Flight mass analyser. 
     
     
       19. A mass spectrometer as claimed in  claim 16 , wherein said ion trap is arranged and adapted to repeatedly pulse ions into said ion mobility separator. 
     
     
       20. A mass spectrometer as claimed in  claim 16 , further comprising an ion source selected from the group consisting of: (i) an Electrospray Ionisations (“ESI”) ion source; (ii) an Atmospheric Pressure Photo Ionisations (“APPI”) ion source; (iii) an Atmospheric Pressure Chemical Ionisations (“APCI”) ion source; (iv) a Matrix Assisted Laser Desorption Ionisations (“MALDI”) ion source; (v) a Laser Desoprtion Ionisations (“LDI) ion source; and (vi) an Atmospheric Pressure Ionisations (“API”) ion source. 
     
     
       21. A mass spectrometer comprising:
 an ion mobility separator; 
 an ion guide arranged downstream of said ion mobility separator, said ion guide being arranged to receive ions from said ion mobility separator; and 
 a mass analyser disposed downstream of said ion guide.